Attachment of a first component to a second component for any of a variety of applications may be made by any of several known methods of fastening, including mechanical or chemical fastening. Mechanical fastening, while often practical and reliable, is not always usable for every application. For example, where a first component is being attached to a second component and it is not desirable or practical to drill into or otherwise modify the second component for mechanical attachment, chemical fastening is the only other alternative. This is the case where, for example, a component is to be attached to a glass surface or other substrate (the second component). An example of a component-to-glass arrangement may be seen in the automotive industry where a rear view mirror or a metal hinge needs to be attached to a glass surface. Other examples of component-to-glass attachment needs exist such as in home and office construction.
A solution to the bonding challenge was introduced in the form of an adhesive applied between the part to be attached (the bonding part) and the substrate to which the bonding part was attached. The adhesives have been applied in several ways.
According to one known approach, the adhesive is applied to the bonding part by dosing with nozzles and spraying the adhesive onto the bonding part. While this process can be easy and often inexpensive, it suffers from the need to frequently clean the nozzles in order to maintain a desired level of consistency in the actual spraying from part to part. In addition, the sprayed adhesive tends to be sticky, thus resulting in the possibility that the bonding part will come into contact with another object between the time of the spraying of the adhesive and the actual attachment of the bonding part to the substrate.
According to another known approach, a double-sided tape is applied to the bonding part. According to this approach a release layer is removed from one side of the tape and the tape is applied to the bonding part. The release layer on the other side of the tape is left in place until the bonding part is ready for attachment to the substrate. This approach offers advantages in that it is usable at room temperature and the adhesive for contact with the substrate is not exposed until needed. Furthermore, the adhesive does not require an adhesion promoter. However, while the release layer protects against the adhesive from being inadvertently attached to a surface, it also adds an inconvenient step in the process of attachment of the bonding part to the substrate in that the layer must be removed prior to attachment. The release layer may also tear, thus resulting in a portion of the layer being left behind on the adhesive surface and creating the potential for imperfect adhesion of the bonding part to the substrate. The step of attaching the double-sided tape to the bonding part is also complicated by the fact that this arrangement of structural adhesives can only be used for in-line assembly in which the bonding part, the double-sided tape and the substrate pass through a heater such as an autoclave to achieve full bonding performance.
A third and more attractive method is to provide the bonding part with a formed adhesive element such as a tablet already in position prior to shipment of the bonding part to the end-user. This arrangement is attractive as it results in a bonding part that is ready to bond with no requirement that the end user attach the adhesive tablet to the bonding part. However, it may be that the end user wishes to apply the tablet at its facility and according to its own schedule and arrangement. In such a case, the concept of a pre-applied adhesive such as the bonding tablet already fitted to the bonding part may not be the optimal choice.
Accordingly, as in so many areas of fastener technology, there is room in the art of bonding parts for an alternate approach to the manufacture of bonding parts.